const modifier at end of signature

This is a discussion on const modifier at end of signature within the C++ Programming forums, part of the General Programming Boards category; Code:
unsigned int Drib::nextBird(unsigned int visibility)//having a const here screws things up
{
return dielema.nextBird(visibility);
}
dielema is an instance ...

Marking a method as const means that it won't modify any member variables of that object. I'm assuming dielema is a member variable of the class? If that's the case, then you cannot call a non-const member variable of the dielema class because non-const functions are allowed to modify the state of the class.

I thought declaring a method as const just means that it's not going to change any of the private data members?

No, it means that the method promises to not change any members, not just private ones but public and protected as well (excluding mutable).
It wont allow you to make that promise if it sees that the function is calling a method which itself doesn't also make that promise.